This invention relates to high pass, low pass and band-pass filters for use within data, FM audio and telephone transceivers. Since all passive-component and most active-component filters include reactive components having frequency-dependent impedance and phase characteristics, and since the reactive components store energy in either magnetic or electrostatic fields, the energy storage results in a memory of previous events such that the filters exhibts a relatively slow response time. The slow response time inherent within state of the art filters results in a sloping frequency response in both amplitude and phase whereas abrupt frequency response and zero phase is required within quality transceivers. One such transceiver is disclosed within U.S. patent application Ser. No. 561,483 filed December 13, 1983 in the name of E. K. Howell. This application is incorporated herein for purposes of reference and provides a detailed description of a digital data transceiver circuit.
The purpose of this invention is to provide a time domain filter wherein the time response is controlled in such a manner that virtually ideal frequency response as well as zero phase conditions are achieved.